Apparatus and method for defining physical channel transmit/receive timings and resource allocation in tdd communication system supporting carrier aggregation

ABSTRACT

A method of defining physical channel transmit/receiving timings and resource allocation is provided for use in a Time Division Duplex (TDD) communication system supporting carrier aggregation. A method for receiving, at a base station, a Hybrid Automatic Repeat Request (HARQ) acknowledgement from a terminal in a Time Division Duplex (TDD) system supporting carrier aggregation of a primary cell and at least one secondary cell includes transmitting a downlink physical channel through one of the primary and secondary cells, receiving the HARQ acknowledgement corresponding to the downlink physical channel of the primary cell at a first timing predetermined for the primary cell, and receiving the HARQ acknowledgement corresponding to the downlink physical channel of the secondary cell at second timing, wherein the second timing is determined according to the first timing.

PRIORITY

This is a continuation application of prior U.S. application Ser. No.14/605,422, filed on Jan. 26, 2015, and will issue as U.S. Pat. No.9,608,775 on Mar. 28, 2017, which is a continuation application of priorU.S. application Ser. No. 13/485,838, filed May 31, 2012, which issuedas U.S. Pat. No. 8,942,202 on Jan. 27, 2015, and which claims thebenefit under 35 U.S.C. §119(a) of a Korean patent application filed onMay 31, 2011 in the Korean Intellectual Property Office and assignedSerial No. 10-2011-0051990, and of a Korean patent application filed onJul. 12, 2011 in the Korean Intellectual Property Office and assignedSerial No. 10-2011-0069119, and of a Korean patent application filed onDec. 20, 2011 in the Korean Intellectual Property Office and assignedSerial No. 10-2011-0138471, the entire disclosures of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication system. Moreparticularly, the present invention relates to a method for definingphysical channel transmit/receiving timings and resource allocation in aTime Division Duplex (TDD) communication system supporting carrieraggregation.

2. Description of the Related Art

The mobile communication system has evolved into a high-speed,high-quality wireless packet data communication system (such as 3rdGeneration Partnership Project (3GPP) High Speed Packet Access (HSPA)and Long Term Evolution (LTE), 3GPP2 High Rate Packet Data (HRPD), UltraMobile Broadband (UMB), and Institute of Electrical and ElectronicsEngineers (IEEE) 802.16e standard systems) to provide data andmultimedia services beyond voice-oriented services.

As a representative broadband radio communication standard, LTE adoptsOrthogonal Frequency Division Multiplexing (OFDM) in the downlink andSingle Carrier Frequency Division Multiple Access (SC-FDMA) in theuplink. Such a multiple access technique is characterized in that thetime-frequency resources carrying data or control information arearranged orthogonally to discriminate among the per-user data and/orcontrol information.

In order to prepare against a decoding failure that occurs at initialtransmission, LTE adopts Hybrid Automatic Repeat Request (HARQ) forretransmission of the decoding-failed data on the physical layer.

HARQ is a technique in which, when decoding fails, the receiver sendsthe transmitter a Negative ACKnowledgement (NACK) such that thetransmitter retransmits the decoding-failed data. If the data is decodedsuccessfully, the receiver sends the transmitter an ACKnowledgement(ACK) such that the transmitter sends new data.

One of the important features of the broadband communication system isto support a scalable bandwidth for providing a high speed data service.For example, the Long Term Evolution (LTE) system can support variousbandwidths, e.g., 20/15/5/3/1.4 Mhz. The service providers can providethe service on a specific bandwidth selected among the diversebandwidths. Likewise, there can be various terminals having differentLTE capabilities for supporting a minimum 1.4 MHz bandwidth and up to a20 MHz bandwidth.

Meanwhile, LTE-Advanced (LTE-A) aiming to meet the IMT-Advancedrequirements can provide a broadband service at a data rate of up to 100MHz through carrier aggregation. In order to support the high data ratetransmission, the LTE-A system requires a bandwidth wider than that ofthe LTE system while preserving backward compatibility to the legacysystems for supporting LTE User Equipment (UE). For backwardcompatibility, system bandwidth of the LTE-A system is divided into aplurality of subbands or Component Carriers (CC) that can be used fortransmission/reception of LTE UEs and aggregated for the high data ratetransmission of the LTE-A system with the transmission/reception processof the legacy LTE system per component carrier.

Typically, the scheduling information for the data to be transmitted onthe component carriers is transmitted to the UE in Downlink ControlInformation (DCI). The DCI can be defined in various formats, and one ofthe predefined DCI formats can be used according to whether schedulinginformation is for uplink or downlink, whether the DCI is compact DCI,whether spatial multiplexing with multiple antennas is applied, andwhether the DCI is the power control DCI. For example, the DCI format 1carrying the control information on the uplink data transmitted withoutapplication of Multiple Input Multiple Output (MIMO) can include thefollowing control information.

-   -   Resource allocation type 0/1 flag: to differentiate between        resource allocation type 0 and resource allocation type 1. Type        0 allocates resources in a unit of Resource Block Groups (RBGs)        using a bitmap format. In the LTE/LTE-A system, the scheduling        resource unit is a Resource Block (RB) representing time and        frequency resource region, and each RBG can be composed of a        plurality of RBs. The RBG can be a basic unit of scheduling        resources in type 0. In type 1, specific RB can be allocated in        the RBG.    -   Resource block assignment: to indicate resource blocks to be        assigned to the UE. The basic unit of radio resource allocation        is an RB representing a time and frequency region.    -   Modulation and coding scheme and redundancy version: to indicate        modulation scheme and coding rate used in data transmission.    -   HARQ process number: to indicate the number of a HARQ process.    -   New Data Indicator (NDI): to indicate whether the packet is a        new transmission or a retransmission.    -   Redundancy version: to indicate the redundancy version of HARQ.    -   Transmission Power Control (TPC) command for Physical Uplink        Shared Channel (PUSCH): to indicate TPC command for PUSCH.

The DCI is channel-coded and modulated and then transmitted on aPhysical Downlink Control Channel (PDCCH).

FIG. 1 is a diagram illustrating a principle of self-scheduling in anLTE-A system supporting carrier aggregation according to the relatedart. FIG. 1 is directed to a situation where an evolved Node B (eNB)schedules downlink data of a UE in an LTE-A system operating with twocomponent carriers (e.g., CC#1 and CC#2).

Referring to FIG. 1, the DCI 101 transmitted on the CC#1 109 isformatted as defined in the legacy LTE standard, channel-coded, and theninterleaved to generate PDCCH 103. The PDCCH 103 carries the schedulinginformation 113 about the PDCCH as the data channel allocated to the UEon the CC#1 109. The DCI 105 transmitted on the CC#2 111 is formatted asdefined in the legacy LTE standard, channel-coded, and then interleavedto generate PDCCH 107. The PDCCH 107 carries the scheduling information115 about a Physical Downlink Shared Channel (PDSCH) as the data channelallocated to the UE on the CC#2 111.

In the LTE-A system supporting carrier aggregation, the data and/or DCIfor supporting the data transmission can be transmitted per componentcarrier as shown in FIG. 1. Such a scheduling technique is referred toas self-scheduling. In a case of DCI, however, it can be transmitted onanother component carrier different form the component carrier carryingthe data, and this is referred to as cross carrier scheduling. In theexemplary case of FIG. 1, when it is difficult to expect highreliability of DCI reception performance due to high interference on theCC#2, the DCI can be transmitted on the CC#1, which is experiencingrelatively low interference.

In a case of PDSCH carrying data, it is possible to overcome theinterference with frequency selective scheduling or HARQ. In a case ofPDCCH carrying DCI, however, HARQ is not applied and it is not possibleto apply the frequency selective scheduling due to system band-widetransmission characteristic and thus there is a need of a method formitigating interference.

FIG. 2 is a diagram illustrating a principle of cross carrier schedulingin an LTE-A system supporting carrier aggregation according to therelated art. FIG. 2 is directed to an exemplary cross carrier schedulingfor an LTE-A UE operating on two aggregated carriers CC#1 209 and CC#2219. It is assumed that CC#2 experiences relatively large interferenceas compared to CC#1 such that, when transmitting DCI as the schedulinginformation for the data transmission on CC#2, it is difficult to expectsatisfactory DCI reception performance.

Referring to FIG. 2, the eNB can transmit the DCI on CC#1 209. In orderto support the cross carrier scheduling, the eNB transmits a CarrierIndicator (CI) indicating the component carrier targeted by the DCIalong with the DCI indicating the resource allocation information andtransmission format of the scheduled data. For example, CI=‘00’indicates CC#1 209 and, CI=‘01’ indicates CC#2 219.

The eNB combines the DCI 201 indicating resource allocation informationand transmission format of the scheduled data 207 and the carrierindicator 202 to generate an extended DCI. The eNB performs channelcoding, modulation, and interleaving on the extended DCI to generate aPDCCH 205. Here, the eNB maps the extended DCI to a respective region ofthe PDCCH 205 of CC#1 209.

The eNB combines the DCI 211 indicating the resource allocationinformation and transmission format of the data 217 scheduled on CC#2and the carrier indicator 212 to generate an extended DCI. Next, the eNBmaps the extended DCI to a respective region of the PDCCH 205 of CC#1209.

The Time Division Duplex (TDD) system uses a common frequency for uplinkand downlink which are discriminated in the time domain. In LTE andLTE-A TDD systems, the uplink and downlink signals are discriminated bysubframe. A radio frame can be divided into equal number of uplink anddownlink subframes according to the uplink and downlink traffic load.The number of uplink subframes may be greater than that of the downlinksubframes and vice versa. In the LTE system, the subframe has a lengthof 1 ms, 10 subframes form a radio frame.

TABLE 1 Uplink-downlink Subframe number configuration 0 1 2 3 4 5 6 7 89 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 DS U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U UU D S U U D

Table 1 shows TDD configurations (TDD uplink-downlink configurations)defined in the LTE standard. In Table 1, subframe numbers 0 to 9indicate the indices of subframes constituting one radio frame. Here,‘D’ denotes a subframe reserved for downlink transmission, ‘U’ denotes asubframe reserved for uplink transmission, and ‘S’ denotes a specialsubframe.

Downlink Pilot Time Slot (DwPTS) can carry the downlink controlinformation as the normal subframe does. If the DwPTS is long enoughaccording to the configuration state of the special subframe, it ispossible to carry the downlink data too. Guard Period (GP) is theinterval used for a downlink-to-uplink switch and its length isdetermined according to the network configuration. Uplink Pilot TimeSlot (UpPTS) can be used for transmitting a UE's Sounding ReferenceSignal (SRS) for uplink channel state estimation and a UE's RandomAccess Channel (RACH).

In a case of TDD uplink-downlink configuration #6, the eNB can transmitdownlink data and/or control information at subframes #0, #5, and #9 anduplink data and/control information at subframes #2, #3, #4, #7, and #8.Here, # indicates number or index. The subframes #1 and #6 as specialsubframes can be used for transmitting downlink control informationand/or downlink data selectively and SRS or RACH in uplink.

Since the downlink or uplink transmission is allowed for specific timeduration in the TDD system, the timing relationship among the uplink anddownlink physical channels such as control channel for data scheduling,scheduled data channel, and HARQ ACK/NACK channel (HARQ acknowledgement)corresponding to the data channel should be defined.

In LTE and LTE-A TDD systems, the timing relationship between PDSCH andPhysical Uplink Control channel (PUCCH) carrying uplink HARQ ACK/NACKcorresponding to the PDSCH or PUSCH is as follows.

The UE receives the PDSCH transmitted by the eNB at an (n-k)^(th)subframe and transmits an uplink HARQ ACK/NACK corresponding to thereceived PDSCH at an n^(th) subframe. Here, k denotes an element of aset K, and K is defined as shown in Table 2.

TABLE 2 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 —— 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, — —4, 6 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, — — — —— — 4, 7 5 — — 13, 12, 9, 8, 7, 5, — — — — — — — 4, 11, 6 6 — — 7 7 5 —— 7 7 —

FIG. 3 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK in a legacy LTE system operating with TDDuplink-downlink configuration #6 according to the related art. FIG. 3shows which subframe carries uplink HARQ ACK/NACK corresponding to PDSCHthat is transmitted in a downlink subframe or a special subframe in TDDuplink-downlink configuration #6 as defined in Table 2.

For example, the UE transmits, at subframe #7 of i^(th) radio frame, theuplink HARQ ACK/NACK 303 corresponding to the PDSCH 301 transmitted bythe eNB at subframe #1 of i^(th) subframe. At this time, the DCIincluding the scheduling information on the PDSCH 301 is transmittedthrough a PDCCH of the subframe which also carries the PDSCH. Foranother example, the UE transmits, at the subframe #4 of (i+1)^(th)radio frame, the uplink HARQ ACK/NACK 307 corresponding to PDSCH 305transmitted by the eNB at subframe #9 of the i^(th) radio frame.Likewise, the DCI including the scheduling information on the PDSCH 305is transmitted through the PDCCH of the subframe which also carriesPDSCH.

The LTE and LTE-A systems adopt an asynchronous HARQ in the downlink inwhich the data retransmission timing is not fixed. That is, when an HARQACK fed back by the UE in response to the HARQ initial transmission datatransmitted by the eNB is received, the eNB determines the next HARQretransmission timing freely according to the scheduling operation. TheUE buffers the data that failed in decoding for a HARQ operation andcombines the buffered data with the next HARQ retransmission data. Inorder to keep the reception buffer space to a predetermined level, amaximum number of HARQ processes are defined per TDD uplink-downlinkconfiguration as shown in Table 3. One HARQ process is mapped to onesubframe in time domain.

TABLE 3 TDD UL/DL Maximum number of HARQ configuration processes 0 4 1 72 10 3 9 4 12 5 15 6 6

Referring to Table 3, if the PDSCH 301 transmitted by the eNB atsubframe #0 of the i^(th) radio frame fails to decode, the UE transmitsan HARQ NACK at the subframe #7 of i^(th) radio frame. Upon receipt ofthe HARQ NACK, the eNB configures the retransmission data correspondingto PDSCH 301 as PDSCH 309 and transmits the PDSCH 309 along with thePDCCH. In the exemplary case of FIG. 3, the retransmission data istransmitted in the subframe #1 of (i+1)^(th) radio frame by takingnotice that the maximum number of downlink HARQ processes is 6 in theTDD uplink-downlink configuration #6 according to the definition ofTable 3. This means that there are a total of 6 downlink HARQ processes311, 312, 313, 314, 315, and 316 between the initial transmission, i.e.,PDSCH 301, and the retransmission, i.e., PDSCH 309.

In order to apply the timing relationships between a physical channel,which are specified for use in the LTE TDD system, to the LTE-A system,extra operations, in addition to the conventional timing relationships,should be defined. In more detail, there is a need for defining thetiming relationship among the PDCCH, PDSCH and uplink HARQ ACK/NACK, anda method for allocating uplink HARQ ACK/NACK transmission resources forsupporting self-scheduling and/or cross carrier scheduling in thesituation where the TDD uplink-downlink configurations are adopted tothe respective carriers aggregated differ from each other.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention to define the timing relationship among Physical DownlinkControl Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), anduplink Hybrid Automatic Repeat Request (HARQ) ACKnowledgement(ACK)/Negative ACK (NACK) and provide a method for allocating uplinkHARQ ACK/NACK transmission resources in a Time Division Duplex (TDD)wireless communication system achieving broadband resources with carrieraggregation, especially when the aggregated carriers use different TDDuplink-downlink configurations.

In accordance with an aspect of the present invention, a method forreceiving, at a base station, a HARQ acknowledgement from a terminal ina TDD system supporting carrier aggregation of a primary cell and atleast one secondary cell is provided. The method includes transmitting adownlink physical channel through one of the primary and secondarycells, receiving the HARQ acknowledgement corresponding to the downlinkphysical channel of the primary cell at a first timing predetermined forthe primary cell, and receiving the HARQ acknowledgement correspondingto the downlink physical channel of the secondary cell at second timing,wherein the second timing is determined according to the first timing.

In accordance with another aspect of the present invention, a method fortransmitting, at a terminal, a HARQ acknowledgement to a base station ina TDD system supporting carrier aggregation of a primary cell and atleast one secondary cell is provided. The method includes receiving adownlink physical channel through one of the primary and second cells,transmitting the HARQ acknowledgement corresponding to the downlinkphysical channel of the primary cell at a first timing predetermined forthe primary cell, and transmitting the HARQ acknowledgementcorresponding to the downlink physical channel of the secondary cell ata second timing, wherein the second timing is determined according tothe first timing.

In accordance with still another aspect of the present invention, aterminal for transmitting a HARQ acknowledgement to a base station in aTDD system supporting carrier aggregation of a primary cell and at leastone secondary cell is provided. The terminal includes a transceiverwhich transmits and receives to and form a base station, and acontroller which controls receiving a downlink physical channel throughone of the primary and second cells, transmitting the HARQacknowledgement corresponding to the downlink physical channel of theprimary cell at a first timing predetermined for the primary cell, andtransmitting the HARQ acknowledgement corresponding to the downlinkphysical channel of the secondary cell at a second timing, whereincontroller configures the second timing according to the first timing.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating a principle of self-scheduling in aLong Term Evolution-Advanced (LTE-A) system supporting carrieraggregation according to the related art;

FIG. 2 is a diagram illustrating a principle of cross carrier schedulingin an LTE-A system supporting carrier aggregation according to therelated art;

FIG. 3 is a diagram illustrating a timing relationship between aPhysical Downlink Shared Channel (PDSCH) and uplink Hybrid AutomaticRepeat Request (HARQ) ACKnowledgement (ACK)/Negative ACK (NACK) in alegacy Long Term Evolution (LTE) system operating with Time DivisionDuplex (TDD) uplink-downlink configuration #6 according to the relatedart;

FIG. 4 is a diagram illustrating a timing relationship among physicalchannels for use in a case where TDD uplink-downlink configurations ofaggregated carriers are identical with each other according to anexemplary embodiment of the present invention;

FIG. 5 is a diagram illustrating a timing relationship among physicalchannels for use in a case where TDD uplink-downlink configurations ofaggregated carriers differ from each other according to an exemplaryembodiment of the present invention;

FIG. 6 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a first exemplary embodiment ofthe present invention;

FIG. 7 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a second exemplary embodimentof the present invention;

FIG. 8 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a third exemplary embodiment ofthe present invention;

FIG. 9 is a flowchart illustrating an evolved Node B (eNB) procedure ina method according to any of the first to third exemplary embodiments ofthe present invention;

FIG. 10 is a flowchart illustrating a User Equipment (UE) procedure in amethod according to any of the first to third exemplary embodiments ofthe present invention;

FIG. 11 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a fourth exemplary embodimentof the present invention;

FIG. 12 is a block diagram illustrating a configuration of an eNBaccording to any of the first to fourth exemplary embodiments of thepresent invention; and

FIG. 13 is a block diagram illustrating a configuration of a UEaccording to any of the first to fourth exemplary embodiments of thepresent invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

In the following description, a Base Station (BS) is an entity forallocating resources to a terminal and can be any of an enhanced Node B(eNB), a Node B, a BS, a radio access unit, a base station controller,and a node on a network.

The terminal can be a User Equipment (UE), a Mobile Station (MS), acellular phone, a smartphone, a computer, or a multimedia systemequipped with communication function. Although the present descriptionis directed to the Advanced Evolved-Universal Mobile TelecommunicationsSystem (UMTS) Terrestrial Radio Access Network (E-UTRA) (or Long TermEvolution-Advanced (LTE-A)) supporting carrier aggregation, the presentinvention can be applied to other communication systems having similartechnical background and channel format, with a slight modification,without departing from the spirit and scope of the present invention.For example, the timing relationship defined according to an aspect ofan exemplary embodiment of the present invention can be applied to amulticarrier High Speed Packet Access (HSPA) system supporting carrieraggregation.

In the LTE-A system supporting carrier aggregation, if the componentcarrier carrying Downlink Control Information (DCI) for datatransmission and the component carrier carrying the data scheduled asindicated by the DCI differ from each other, this is referred to ascross carrier scheduling. Meanwhile, if the component carrier carryingthe DCI for data transmission and the component carrier carrying thedata scheduled as indicated by the DCI are identical with each other,this is referred to as self-scheduling.

In the LTE-A system supporting carrier aggregation, if the probabilityof inter-carrier interference between the aggregated component carriersis low since the frequency bands of the carriers are not adjacent, it ispossible to set the component carriers with different Time DivisionDuplex (TDD) uplink-downlink configurations. For example, the firstcomponent carrier can be configured to operate with the uplink anddownlink subframes equal in number while the second component carrier isconfigured to operate with the downlink subframes larger than uplinksubframes in number to increase downlink transmission capacity. Foranother example, the first component carrier can be configured tooperate with the TDD uplink-downlink configuration supportingcompatibility with Time Division-Synchronous Code Division MultipleAccess (TD-SCDMA) as a legacy 3^(rd) Generation (3G) TDD system to avoidinterference between TD-SCDMA and Long Term Evolution (LTE) TDD systemswhile the second component carrier is configured with a TDDuplink-downlink configuration determined according to the traffic loadwithout extra restriction.

A description is made of the carrier aggregation system including aPrimary Cell (PCell) and a Secondary Cell (SCell). The PCell (or firsttype cell) provides the UE with basic radio resources on a primaryfrequency (or Primary Component Carrier; PCC) and is the cell to whichthe UE attempts initial connection or handover. The SCell (or secondtype cell) provides the UE with additional resources on the secondaryfrequency (or Secondary Component Carrier; SCC). It is assumed that aHybrid Automatic Repeat Request (HARQ) ACKnowledgement (ACK)/NegativeACK (NACK) which the UE feeds back to the eNB is configured into aPhysical Uplink Control Channel (PUCCH) and then transmitted through thePCell.

The subject matter of the present disclosure is to define the timingrelationship among a Physical Downlink Control Channel (PDCCH), aPhysical Downlink Shared Channel (PDSCH), and an uplink HARQ ACK/NACKand provide a method for allocating uplink HARQ ACK/NACK transmissionresources in the TDD wireless communication system securing broadbandresources through carrier aggregation, especially when theself-scheduling or cross carrier scheduling is selectively applied dueto the difference between the TDD uplink-downlink configurations of theaggregated carriers.

FIG. 4 is a diagram illustrating a timing relationship among physicalchannels for use in a case where TDD uplink-downlink configurations ofaggregated carriers are identical with each other according to anexemplary embodiment of the present invention. FIG. 4 is directed to anexemplary case where both the PCell and SCell use the TDDuplink-downlink configuration #1.

Referring to FIG. 4, the eNB transmits PDSCH 407 to be transmittedthrough the PCell 401 and PDCCH 405 for scheduling PDSCH 407 at thesubframe #0. The eNB also transmits PDSCH 413 to be transmitted throughthe SCell 403 and PDCCH 411 for scheduling the PDSCH 413 at the subframe#0. At this time, the transmission timing of the HARQ ACK/NACKcorresponding to the PDSCHs 407 and 413 becomes the subframe #7according to the timing relationship defined in the TDD uplink-downlinkconfiguration #1. The UE transmits the HARQ ACK/NACKs corresponding tothe respective PDSCHs 407 and 413 at the subframe #7 409 through thePCell 401.

FIG. 5 is a diagram illustrating a timing relationship among physicalchannels for use in a case where TDD uplink-downlink configurations ofaggregated carriers differ from each other according to an exemplaryembodiment of the present invention. FIG. 5 is directed to an exemplarycase where the PCell 501 is configured with the TDD uplink-downlinkconfiguration #3 (TDD UL/DL configuration #3) while the SCell 503 isconfigured with the TDD uplink-downlink configuration #1 (TDD UL/DLconfiguration #1).

Referring to FIG. 5, the eNB transmits PDSCH 507 to be transmittedthrough PCell 501 and PDCCH 505 for scheduling the PDSCH 507 at thesubframe #0. The transmission timing of the HARQ ACK/NACK correspondingto the PDSCH 507 becomes the subframe #4 509 according to the timingrelationship defined in the TDD uplink-downlink configuration #3.Accordingly, the UE transmits the HARQ ACK/NACK corresponding to thePDSCH 507 at the subframe #4 509 through the Pcell 501.

The eNB also transmits the PDSCH 513 to be transmitted through the SCell503 and the PDCCH 511 for scheduling the PDSCH 513 at the subframe #0.At this time, the transmission timing of the HARQ ACK/NACK correspondingto the PDSCH 513 becomes the subframe #7 515 according to the timingrelationship defined in the TDD uplink-downlink configuration #1.However, since the subframe #7 517 carrying the HARQ ACK/NACK is aDownLink (DL) subframe in view of the PCell, it is not possible totransmit an uplink signal.

In order to address this problem, an exemplary embodiment of the presentinvention proposes the following rules. The rules can be commonlyapplied to both the cross carrier scheduling and self-scheduling.

-   -   Rule 1: The HARQ ACK/NACK transmission timing of the UE in a        PCell is fixed regardless of whether the carrier aggregation is        applied or not.    -   Rule 2: The transmission timings of the HARQ ACK/NACK        corresponding to the PDSCH to be transmitted through the PCell        and the PDSCH to be transmitted through the SCell are identical        with each other.    -   Rule 3: The transmission timing n′ of the HARQ ACK/NACK        corresponding to the PDSCH transmitted at an n^(th) subframe is        equal to or greater than the transmission timing m′ of the HARQ        ACK/NACK corresponding to the PDSCH transmitted at an m^(th)        subframe (m<n, m′≦n′). The UE transmits the HARQ ACK/NACK at the        UpLink (UL) subframe of a PCell among the subframes satisfying        the relationship n′=n+k and m′=m+k (k≧4) after the receipt of        the PDSCH. Here, k is set to a value equal to or greater than 4        in consideration of the PDSCH reception processing time and HARQ        ACK/NACK transmission processing time.    -   Rule 4: The transmission timings of the HARQ ACK/NACK        corresponding to the PDSCH transmitted at each DL subframe are        distributed in the UL subframe as equally as possible.

Hereinafter, a description is made of a method for defining a timingrelationship among the PDCCH, PDSCH, and uplink HARQ ACK/NACK that arerelated to the downlink data transmission. The present invention can beapplied without any restriction on the number of component carriers tobe aggregated for securing a broadband resource.

The first to third exemplary embodiments are directed to the case wherethe number of UL subframes according to the TDD uplink-downlinkconfiguration of the PCell is greater than the number of UL subframesaccording to the TDD uplink-downlink configuration of the SCell. Also,it is assumed that, if the SCell is at an UL subframe, the PCell is alsoat an UL subframe at the same timing. That is, in view of an ULsubframe, the position of the UL subframe in the PCell is always superset as compared to the UL subframe in the SCell

The fourth exemplary embodiment is directed to the case where any of theabove restrictions is not applied in the TDD uplink-downlinkconfigurations of the PCell and SCell.

First Exemplary Embodiment

The first exemplary embodiment is directed to the case where the TDDuplink-downlink configurations of the aggregated carriers differ fromeach other in the TDD wireless communication system securing broadbandresources through carrier aggregation. The timing relationship among thePDCCH, PDSCH, and PUCCH for transmitting uplink HARQ ACK/NACK that arerelated to downlink data transmission is described in association withrules 1 to 3.

FIG. 6 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a first exemplary embodiment ofthe present invention. FIG. 6 is directed to an exemplary case where thePCell is configured with the TDD uplink-downlink configuration #3 601and the SCell is configuration with the TDD uplink-downlinkconfiguration #4 602 in the TDD system operating on the componentcarriers aggregated. Here, ‘D’ denotes a DL subframe, ‘U’ denotes an ULsubframe, and ‘S’ denotes a special subframe.

Referring to FIG. 6, the timing relationship among PDCCH, PDSCH, andPUSCH for PCell that is defined in the legacy LTE system and the timingrelationship among PDCCH, PDSCH, and PUSCH for SCell that is defined inthe legacy LTE system are expressed using solid line arrows. The timingrelationships for the PCell and SCell that are expressed with the solidline arrows follow the timing relationships defined in the TDDuplink-downlink configurations #3 and #4, respectively.

In a case where the timing relationship is defined so as to transmit x(x>0) HARQ ACK/NACK is transmitted at a UL subframe, the UE transmits upto x HARQ ACK/NACK in the PUCCH at the UL subframe. If the UE does notschedule the PDSCH for the UE at some DL subframes corresponding to theUL subframe, or if the UE fails to receive the PDSCH transmitted by theeNB, the PUSCH carries y (y<x) HARQ ACK/NACK.

The start point of each solid line arrow denotes the DL subframecarrying the PDCCH and PDSCH. The end point of each solid line arrowdenotes the UL subframe carrying the PUSCH. For example, the HARQACK/NACKs corresponding to the respective PDSCHs transmitted at subframe#7 613 and subframe #8 614 of i^(th) subframe 604 of the PCell areformatted into the PUCCH transmitted at the subframe #3 619 of(i+1)^(th) radio frame 605 of the PCell.

The transmission timing of the PUSCH carrying the HARQ ACK/NACKscorresponding to the PDSCHs transmitted at the subframes #6 627,subframe #7 628, subframe #8 629, and subframe #9 630 follows the timingrelationship defined in the TDD uplink-downlink configuration #4 so asto be transmitted at the subframe #3 634 of the (i+1)^(th) radio frame605. However, since the PUSCH can be transmitted through the PCell, theHARQ ACK/NACKs corresponding to the PDSCHs transmitted at the subframes#6 627, subframe #7 628, subframe #8 629, and subframe #9 630 of thei^(th) radio frame 604 are transmitted at the subframe #3 619 of thePCell.

However, if following the timing relationships of the LTE system thatare defined for the respective PCell and SCell, although the PDSCH istransmitted through the PCell and SCell at the same timing, thetransmission timing of the HARQ ACK/NACK corresponding to the PDSCH ofthe PCell and the transmission timing of the HARQ ACK/NACK correspondingto PDSCH of the SCell differ from each other so as to increase systemoperation complexity and degrade the efficiency. For example, the HARQACK/NACK corresponding to the PDSCH transmitted at the subframe #6 612of the i^(th) radio frame of the PCell is transmitted at the subframe #2of (i+1)^(th) radio frame of the PCell. However, the HARQ ACK/NACKcorresponding to the PDSCH transmitted at the subframe #6 of the i^(th)radio frame which is identical with the PDSCH of the PCell intransmission timing is transmitted at the subframe #3 619 of the PCellwhich corresponds to the subframe #3 634 of the (i+1)^(th) radio frame.

In order to address this problem, the HARQ ACK/NACK transmission timingof the UE operating on the aggregated carriers is determined accordingto the above described rules 1 and 2, which are repeated below.

-   -   Rule 1: The HARQ ACK/NACK transmission timing of the UE in the        PCell is fixed regardless of whether the carrier aggregation is        applied or not.    -   Rule 2: The transmission timings of the HARQ ACK/NACK        corresponding to the PDSCH to be transmitted through the PCell        and the PDSCH to be transmitted through the SCell are identical        with each other.

Rule 1 is for the PCell to follow the HARQ ACK/NACK transmission timingas indicated in the TDD uplink-downlink configurations specified in LTE.Rule 2 is to follow the HARQ ACK/NACK transmission timing of the PCellaggregated with the SCell as the HARQ ACK/NACK transmission timingcorresponding to the PDSCH transmitted through the SCell regardless ofthe TDD uplink-downlink configuration of the SCell.

There may be no PCell's HARQ ACK/NACK transmission timing to referencefor applying rule 2 to a certain DL subframe of the SCell. In theexemplary case of FIG. 6 the subframe #4 625 of the SCell is the DLsubframe, the subframe #4 of the PCell at the same timing is the ULsubframe. Accordingly, the transmission timing of the HARQ ACK/NACKcorresponding to the PDSCH transmitted at the subframe #4 of the secondcell cannot be determined by referencing the subframe #4 of the PCell.Therefore, the transmission timing of the HARQ ACK/NACK corresponding tothe DL subframe of the SCell is newly defined by applying rule 3, whichis repeated below.

-   -   Rule 3: The transmission timing n′ of the HARQ ACK/NACK        corresponding to the PDSCH transmitted at an n^(th) subframe is        equal to or greater than the transmission timing m′ of the HARQ        ACK/NACK corresponding to the PDSCH transmitted at an m^(th)        subframe (m<n, m′≦n′). The UE transmits the HARQ ACK/NACK at the        UL subframe of a PCell among the subframes satisfying the        relationship n′=n+k and m′=m+k (k≧4) after the receipt of the        PDSCH. Here, k is set to a value equal to or greater than 4 in        consideration of the PDSCH reception processing time and HARQ        ACK/NACK transmission processing time.

With rule 3, the transmission timing of the HARQ ACK/NACK correspondingto the PDSCH transmitted at subframe #4 625 of i^(th) subframe throughthe SCell is determined by referencing the transmission timing of theHARQ ACK/NACK corresponding to the subframe #1 607 and subframe #5 611of the PCell that are DL subframes closest to the subframe #4 back andforth. The transmission timing of the HARQ ACK/NACK corresponding to thesubframe #1 607 of the PCell becomes the subframe #2 618 of (i+1)^(th)subframe, and the transmission timing of the HARQ ACK/NACK correspondingto the subframe #5 611 becomes the subframe #2 618 of (i+1)^(th)subframe too. The transmission timing of the HARQ ACK/NACK correspondingto the PDSCH transmitted at the subframe #4 625 of i^(th) radio framethat satisfies rule 3 in the SCell becomes the subframe #2 618 of the(i+1)^(th) radio frame. In a case where the PDSCH to be transmitted atthe subframe #4 625 of the SCell is cross-carrier scheduled in thePCell, the PDCCH is transmitted at the subframe #1 607 as the DLsubframe of the PCell which is closest to the subframe #4 625. The PDCCHcarried in the subframe #1 607 of the PCell includes an indicator forindicating whether the scheduling is of the PDSCH carried at thesubframe #1 622 of the second cell or the PDSCH carried in the subframe#4 of the SCell.

Rule 3 can be modified as follows.

The subframe of the PCell is configured as a UL subframe at the timingwhen the PDSCH of the SCell is transmitted, the HARQ ACK/NACKcorresponding to the PDSCH of the SCell is transmitted through the PCellaccording to the HARQ ACK/NACK timing defined in the TDD uplink-downlinkconfiguration of the SCell. In this case, the subframe of the PCell atthe transmission timing of the HARQ ACK/NACK is an uplink subframe.

If rules 1, 2, and 3 are applied synthetically, the transmission timingof the HARQ ACK/NACK corresponding to the PDSCH of the SCell can beconfigured as expressed by the dotted line arrows in FIG. 6 as proposedin the present exemplary embodiment.

While FIG. 6 is directed to the case where the cross-carrier schedulingis applied, the present invention is not limited thereto. By applyingrules 1, 2, and 3 synthetically, it is possible to determine thetransmission timing of the HARQ ACK/NACK in the self-scheduling mode asin the cross carrier scheduling. In the exemplary case of FIG. 6, thedotted link arrow starting at a D or S subframe of the PCell and endingat a D or S subframe of the SCell expresses the cross carrier schedulingoperation in which the PDCCH transmitted at the D or S subframe of thePCell schedules the PDSCH to be transmitted at the D or S subframe ofthe SCell. Also, the dotted line arrows starting at the D or S subframeof the SCell and ending at an U subframe of the PCell expresses anoperation in which the HARQ ACK/NACK corresponding to the PDSCHtransmitted at the D or S subframe of the SCell is transmitted at the Usubframe of the PCell.

For example, if the PDCCH is transmitted at the subframe #1 of thei^(th) radio frame of the PCell to cross-carrier schedule the SCell, thePDSCH is transmitted at the subframe #1 622 of the i^(th) radio frame ofthe SCell, and the HARQ ACK/NACK corresponding to the PDSCH of the SCellis transmitted at the subframe #2 618 of the (i+1)^(th) radio frame ofthe PCell according to the transmission timing of the HARQ ACK/NACKcorresponding to the subframe #1 607 of the PCell according to rule 2.

If the PDCCH transmitted at the subframe #1 607 of the i^(th) radioframe of the PCell is cross-carrier scheduling the PDSCH to betransmitted at the subframe #4 625 of the i^(th) radio frame of theSCell, the HARQ ACK/NACK corresponding to the PDSCH of the SCell istransmitted at the subframe #2 618 of the (i+1)^(th) radio frame of thePCell. In this case, although the subframe #4 625 of the SCell is a DLsubframe, the subframe #4 610 of the PCell at the same timing is a ULsubframe. Accordingly, the PDCCH for cross-carrier scheduling the PDSCHto be transmitted at the subframe #4 625 of the SCell is transmitted atthe subframe #1 607 as a DL subframe of the PCell closest to thesubframe #4 625. The transmission timing of the HARQ ACK/NACKcorresponding to the PDSCH to be transmitted through the PCell followsthe HARQ ACK/NACK transmission timing defined in the TDD uplink-downlinkconfiguration #3 predefined according to rule 1.

The HARQ ACK/NACK transmission timing according to the first exemplaryembodiment can be summarized as shown in Table 4. If the PDSCHtransmitted by the eNB at (n−j)^(th) subframe is received, the UEtransmits an uplink HARQ ACK/NACK corresponding to the PDSCH at then^(th) subframe. Here, j is an element of a set J which is defined asshown in Table 4. Table 4 is directed to the case where the PCell isconfigured with the TDD uplink-downlink configuration #3, the SCell isconfigured with the TDD uplink-downlink configuration #4, and the HARQACK/NACKs corresponding to the PDSCHs transmitted through the PCell andSCell are transmitted through the PCell.

TABLE 4 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 3 — — 7, 6,11 6, 5 5, 4 — — — — — 4 — — 7, 6, 8, 6, 5 5, 4 — — — — — 11

Second Exemplary Embodiment

The second exemplary embodiment is directed to the case where the timingrelationship among PDCCH, PDSCH, and PUCCH carrying the uplink HARQACK/NACK that are related to the downlink data transmission with rules 1to 4 in the TDD wireless communication system securing broadbandresource through carrier aggregation, especially when the TDDuplink-downlink configurations of the carriers differ from each other.

FIG. 7 is directed to the TDD system operating with two aggregatedcomponent carriers in which the PCell 701 is configured with the TDDuplink-downlink configuration #6 and the SCell 702 is configured withthe TDD uplink-downlink configuration #2. The PCell's timingrelationship among the PDCCH, PDSCH, and PUCCH that is defined in thelegacy LTE system and the SCell's timing relationship among the PDCCH,PDSCH, and PUCCH that is defined in the legacy LTE system are expressedusing solid link arrows. The start point of each solid line arrowdenotes the DL subframe carrying the PDCCH and PDSCH, and the end pointof each solid link arrow denotes the UL subframe carrying the PUCCH.

FIG. 7 is a diagram illustrating a timing relationship between PDSCH andan uplink HARQ ACK/NACK according to a second exemplary embodiment ofthe present invention.

Referring to FIG. 7, the transmission timing of the HARQ ACK/NACKcorresponding to the PDSCH of the SCell is expressed with a dotted linkarrow. Although the description is directed to the case of using thecross carrier scheduling, the present invention is not limited thereto.That is, a system operating with the self-scheduling can also determinethe HARQ ACK/NACK transmission timing in the same manner as the crosscarrier scheduling.

Here, the dotted link arrows starting at a D or S subframe of the PCelland ending at a D or S subframe of the SCell expresses the cross carrierscheduling operation in which the PDCCH transmitted at the D or Ssubframe of the PCell schedules the PDSCH to be transmitted at the D orS subframe of the SCell. Also, the dotted line arrows starting at the Dor S subframe of the SCell and ending at a U subframe of the PCellexpresses an operation in which the HARQ ACK/NACK corresponding to thePDSCH transmitted at the D or S subframe of the SCell is transmitted atthe U subframe of the PCell.

In FIG. 7, the PCell follows the HARQ ACK/NACK transmission timingdefined in the TDD uplink-downlink configuration #6 according to rule 1regardless of the use of carrier aggregation. The transmission timing ofthe HARQ ACK/NACK corresponding to the PDSCH transmitted through theSCell follows the HARQ ACK/NACK transmission timing of the PCellaggregated with the SCell regardless of the TDD uplink-downlinkconfiguration of the SCell according to rule 2.

If the PDCCH is transmitted at the subframe #1 of i^(th) radio frame ofthe PCell to cross-carrier schedule the SCell, the PDSCH of the SCell istransmitted at the subframe #1 722 of the i^(th) radio frame. The HARQACK/NACK corresponding to the PDSCH of the SCell is transmitted at thesubframe #8 714 of the i^(th) radio frame of the PCell according to thetransmission timing of the HARQ ACK/NACK corresponding to the subframe#1 707 of the PCell according to rule 2.

The PDCCH transmitted at the subframe #1 of the i^(th) radio frame ofPCell is cross-carrier scheduling the PDSCH to be transmitted at thesubframe #3 724 of the i^(th) radio frame, the HARQ ACK/NACKcorresponding to the PDSCH of the SCell may be transmitted earlier thanthe subframe #8 714 as the transmission timing of the HARQ ACK/NACKcorresponding to the PDSCH to be transmitted at the subframe #1 722 ofthe second cell as DL subframe right before according to rule 3.Accordingly, the HARQ ACK/NACK corresponding to the PDSCH transmitted atthe subframe #3 724 of the i^(th) radio frame of the SCell istransmitted at the subframe #8 714 of the i^(th) subframe of the PCell.

The PDCCH transmitted at the subframe #1 707 of the i^(th) radio frameof the Pcell. The PDCCH transmitted at the subframe #1 707 of the i^(th)radio frame of the PCell carries the cross carrier schedulinginformation for the PDSCH to be transmitted at the subframe #4 of thei^(th) radio frame. The HARQ ACK/NACK corresponding to the PDSCH of theSCell is transmitted at the subframe #8 of the (i+1)^(th) radio frame ofthe PCell since it cannot precede the subframe #8 714 as thetransmission timing of the HARQ ACK/NACK corresponding to the PDSCHtransmitted at the subframe #3 724 of the second cell as the DL subframeright before according to rule 3.

The PDCCH is transmitted at the subframe #5 711 of the i^(th) radioframe of the PCell to cross-carrier schedule the SCell, the PDSCH istransmitted at the subframe #5 of the i^(th) radio frame of the secondcell. The HARQ ACK/NACK corresponding to the PDSCH of the SCell istransmitted at the subframe #2 718 of the (i+1)^(th) radio frame of thePCell according to the transmission timing of the HARQ ACK/NACKcorresponding to the subframe #5 711 of the PCell as specified in rule2.

If the PDCCH is transmitted at the subframe #6 of the i^(th) radio frameof the PCell to cross-carrier schedule the SCell, the PDSCH istransmitted at the subframe #6 727 of the i^(th) radio frame through theSCell. The HARQ ACK/NACK corresponding to the PDSCH of the SCell istransmitted at the subframe #3 719 of the (i+1)^(th) radio frame of thePCell according to the transmission timing of the HARQ ACK/NACKcorresponding to the subframe #5 711 of the PCell as specified in rule2.

The PDCCH transmitted at the subframe #6 of the i^(th) radio frame ofthe PCell carries the cross scheduling information for the PDSCH to betransmitted at the subframe #8 of the i^(th) radio frame of the SCell.The HARQ ACK/NACK corresponding to the PDSCH of the SCell is transmittedat the subframe #3 of the (i+1)^(th) radio frame of the PCell since itcannot precede the subframe #3 719 as the transmission timing of theHARQ ACK/NACK corresponding to the PDSCH transmitted at the subframe #6727 of the SCell as the DL subframe right before as specified in rule 3.

Once the HARQ ACK/NACK transmission timing is defined as above, thenumbers of HARQ ACK/NACKs corresponding to the PDSCHs of the SCell thatare transmitted at UL subframes of the PCell has the relationship of (ULsubframe #2:UL subframe #3:UL subframe #4:UL subframe #7:UL subframe#8)=(1:2:1:1:3) such that the number of HARQ ACK/NACKs transmitted atthe UL subframe #8 is relatively large, resulting in an inequality. Thiscauses degradation of the resource utilization efficiency for the HARQACK/NACK transmission.

In order to address this problem, the HARQ ACK/NACK timing is determinedsuch that the HARQ ACK/NACK transmission timings are distributed at theUL subframes of a radio frame as equally as possible with rule 4 inaddition to rules 1 to 3.

-   -   Rule 4: The transmission timings of the HARQ ACK/NACKs        corresponding to the PDSCHs transmitted at the DL subframes are        distributed at the UL subframes as equally as possible.

By adding rule 4 to the scheduling method, it is possible to avoid anexcessive increase of the number of HARQ ACK/NACKs transmitted at acertain subframe. That is, the HARQ ACK/NACK corresponding to the PDSCHtransmitted at the subframe #4 725 of the i^(th) radio frame of theSCell can be transmitted at the subframe #2 718 of the (i+1)^(th) radioframe of the PCell.

By defining the HARQ transmission timing as described above, thedistribution of the HARQ ACK/NACKs corresponding to the PDSCHstransmitted at UL subframes of the PCell and the SCell shows therelationship of (UL subframe #2:UL subframe #3: subframe #4:UL subframe#7:UL subframe #8)=(2:2:1:1:2) distributed as equally as possible. Asshown in FIG. 7, the numbers of the dotted link arrows arriving at theUL subframes of the PCell are equal to each other. Also, thedistribution of the number of the HARQ ACK/NACKs corresponding to thePDSCHs transmitted in view of UL subframes of the PCell has therelationship of (UL subframe #2:UL subframe #3:UL subframe #4:ULsubframe #7:UL subframe #8)=(1:1:1:1:1).

Accordingly, the total distribution of the numbers of HARQ ACK/NACKscorresponding to the PDSCHs transmitted at the PCell and SCell in viewof each UL subframe of the PCell has the relationship of (UL subframe#2:UL subframe #3:UL subframe #4:UL subframe #7:UL subframe#8)=(3:3:2:2:3) distributed as equally as possible.

The HARQ ACK/NACK transmission timings according to the second exemplaryembodiment can be summarized as shown in Table 5. If the PDSCHtransmitted by the eNB at the (n−j)^(th) subframe, the UE transmits theuplink HARQ ACK/NACK corresponding to the PDSCH at n^(th) subframe.Here, j is an element of a set J which is defined as shown in Table 5.Table 5 is directed to the case where the PCell is configured with theTDD uplink-downlink configuration #6, the SCell is configured with theTDD uplink-downlink configuration #2, and the HARQ ACK/NACKscorresponding to the PDSCHs transmitted through the PCell and SCell aretransmitted through the PCell.

TABLE 5 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 2 — — 7, 8 5,7 5 — — 7 5, 7 — 6 — — 7 7 5 — — 7 7 —

Third Exemplary Embodiment

FIG. 8 is a diagram illustrating the timing relationship between thePDSCH and the uplink HARQ ACK/NACK according to the third exemplaryembodiment of the present invention. FIG. 8 shows another exemplaryembodiment to help understand the second exemplary embodiment moreclearly, and is directed to the TDD system operating with two aggregatedcomponent carriers in which the PCell 801 is configured with the TDDuplink-downlink configuration #0 and the SCell 802 is configured withthe TDD uplink-downlink configuration #2. By introducing rule 4 inaddition to rules 1 to 3, the HARQ ACK/NACK transmission timings aredistributed across the UL subframes within a radio frame as equally aspossible.

In this case, the HARQ ACK/NACK transmission timing can be summarized asshown in Table 6. If the PDSCH transmitted by the eNB at the (n−j)^(th)subframe, the UE transmits the uplink HARQ ACK/NACK corresponding to thePDSCH at n^(th) subframe. Here, j is an element of a set J which isdefined as shown in Table 6.

Table 6 is directed to the case where the PCell is configured with theTDD uplink-downlink configuration #0, the SCell is configured with theTDD uplink-downlink configuration #2, and the HARQ ACK/NACKscorresponding to the PDSCHs transmitted through the PCell and SCell aretransmitted through the PCell.

TABLE 6 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 —— 6 — 4 2 — — 6 4, 5 4 — — 6 4, 5 4

By defining the HARQ ACK/NACK transmission timing as described above,the distribution of the numbers of the HARQ ACK/NACKs corresponding tothe PDSCHs transmitted through the SCell in view of the UL subframe ofthe PCell has the relationship of (UL subframe #2:UL subframe #3:ULsubframe #4:UL subframe #7:UL subframe #8:UL subframe #9)=(1:2:1:1:2:1)distributed as equally as possible. As shown in FIG. 8, the numbers ofthe dotted link arrows arriving at the UL subframes of the PCell areequal to each other.

The distribution of the number of the HARQ ACK/NACKs corresponding tothe PDSCHs transmitted in view of UL subframes of the PCell has therelationship of (UL subframe #2:UL subframe #3:UL subframe #4:ULsubframe #7:UL subframe #8:UL subframe #9)=(1:0:1:1:0:1).

Accordingly, the total distribution of the numbers of HARQ ACK/NACKscorresponding to the PDSCHs transmitted at the PCell and SCell in viewof UL subframes of the PCell has the relationship of (UL subframe #2:ULsubframe #3:UL subframe #4:UL subframe #7:UL subframe #8:UL9)=(2:2:2:2:2:2) distributed as equally as possible.

FIG. 9 is a flowchart illustrating an eNB procedure in a methodaccording to any of the first to third exemplary embodiments of thepresent invention.

The operation of the eNB according to an exemplary embodiment of thepresent invention is summarized as follows. The method comprises a stepof transmitting a downlink physical channel for at least one of thefirst cell (PCell) and the second cell (SCell) to the UE, a firstreception step of receiving a physical uplink channel corresponding tothe downlink physical channel of the first cell, and a second receptionstep of receiving a physical uplink channel for a downlink physicalchannel of the second cell according to the reception timing of thephysical uplink channel of the first cell. In this case, the secondreception step can follow rules 1 to 3 described above.

Referring to FIG. 9, a description is made of the eNB procedureaccording to an exemplary embodiment of the present invention in detail.

The eNB sets the transmission timing of PDSCH to n^(th) subframe at step901. Next, the eNB determines whether to transmit the PDSCH through aPCell, an SCell, or both the PCell and SCell, at step 903.

If it is determined to transmit the PDSCH through the PCell, the eNBtransmits to the UE the PDSCH and PDCCH for scheduling the PDSCH at then^(th) subframe of the PCell at step 905. Next, the eNB receives a HARQACK/NACK corresponding to the PDSCH at a UL subframe of the PCellaccording to the HARQ ACK/NACK transmission timing defined for thelegacy LTE system in the TDD uplink-downlink configuration in step 907(rule 1). Next, the eNB determines whether to perform retransmission ofold data or initial transmission of new data according to the receivedHARQ ACK/NACK at step 909. If the ACK is received, the eNB transmits thenew data to the UE. Otherwise, if the NACK is received, the eNBretransmits the PDSCH.

If it is determined to transmit the PDSCH through the SCell at step 903,the eNB checks a subframe state of the PCell and SCell at the n^(th)subframe as the PDSCH transmission timing at step 911.

If the PCell is in the state of a DL subframe or special subframe and ifthe SCell is in the state of the DL subframe or special subframe, theeNB transmits the PDCCH at the n^(th) subframe of the PCell or SCell atstep 913. The PDSCH is transmitted at the n^(th) subframe. At this time,if the system is in self-scheduling mode, the eNB transmits the PDCCH atthe n^(th) subframe of the SCell. If the system is in cross-carrierscheduling mode, the eNB transmits the PDCCH at the n^(th) subframe ofthe PCell. Next, the eNB performs a process for receiving the HARQACK/NACK corresponding to the PDSCH at step 907 (rules 1 and 2).

If the PCell is in the state of a UL subframe and if the SCell is in thestate of a DL subframe or special subframe, the eNB transmits the PDCCHat the closest DL subframe before the n^(th) subframe of the PCell atstep 915. Or, the eNB transmits the PDCCH at the n^(th) subframe of theSCell. Next, the eNB transmits the PDSCH at the n^(th) subframe of theSCell and, if the system is in the cross carrier scheduling mode, theeNB transmits the PDCCH at the closest DL subframe before the n^(th)subframe of the PCell. Afterward, the eNB receives the HARQ ACK/NACK atthe UL subframe of the PCell according to the HARQ ACK/NACK transmissiontiming defined in rule 3 as described in the first exemplary embodimentand the HARQ ACK/NACK transmission timing defined in rules 3 and 4 asdescribed in the second exemplary embodiment at step 917. Next, the eNBcan determine whether to retransmit the PDSCH according to the receivedHARQ ACK/NACK at step 909. If the ACK is received, the eNB transmits newdata to the UE. Otherwise, if the NACK is received, the eNB retransmitsthe PDSCH to the UE. Afterward, the procedure returns to step 901.

Although not depicted in FIG. 9, if the PDSCH is transmitted throughboth the PCell and SCell at step 903, the eNB's PDSCH transmissionprocedure in the PCell goes to step 905. Meanwhile, the eNB's PDSCHtransmission procedure in the SCell goes to step 911.

FIG. 10 is a flowchart illustrating a UE procedure in a method accordingto any of the first to third exemplary embodiments of the presentinvention.

The operation the UE according to an exemplary embodiment of the presentinvention is summarized as follows. The method comprises a step ofreceiving a downlink physical channel for at least one of the first andsecond cells from the eNB, a first transmission step of transmitting theuplink physical channel of the first cell at a predetermined timing, anda second transmission step of transmitting the uplink physical channelof the second cell according to the uplink physical channel transmissiontiming of the first cell. Here, the second transmission step can followrules 1 to 3 described above.

A description is made of the UE procedure according to an exemplaryembodiment of the present invention with reference to FIG. 10.

Referring to FIG. 10, the UE receives a PDCCH at the m^(th) subframefrom the eNB at step 1001. The UE is not aware of the timing andcomponent carrier for PDCCH transmission of the eNB. Accordingly, the UEattempts to decode the PDCCH on all of the aggregated component carriersat every subframe. In more detail, the UE performs a Cyclic RedundancyCheck (CRC) test with a unique UE IDentifier (ID) allocated to itself onthe received PDCCH and, if the CRC test is passed, it is determined thatthe PDCCH is addressed to the UE.

The UE determines whether the received PDCCH is for scheduling the PDSCHof the PCell, the PDSCH of the SCell, or the PDSCHs of both the PCelland SCell at step 1003. If the received PDCCH is for scheduling thePDSCH of the PCell, the UE receives the PDSCH at the m^(th) subframe ofthe PCell at step 1005. Next, the UE transmits the HARQ ACK/NACKcorresponding to the PDSCH at the UL subframe of the PCell according tothe HARQ ACK/NACK transmission timing defined for the legacy LTE systemin the TDD uplink-downlink configuration at step 1007 (rule 1).Afterward, the procedure returns to step 1001.

If the received PDCCH is for scheduling the PDSCH of the SCell at step1003, the UE checks the subframe state of the PCell and SCell at then^(th) subframe as the eNB's PDSCH transmission timing at step 1011. Ifthe PCell is in the state of the DL subframe or special subframe and ifthe SCell is in the state of the DL subframe or special subframe, the UEreceives the PDSCH at the m^(th) subframe of the SCell at step 1013.This is the case of m=n such that the PDCCH and PDSCH are received atthe same subframe. Afterward, the UE performs a process for transmittingthe HARQ ACK/NACK corresponding to the PDSCH at step 1007 (rules 1 and2).

If the PCell is in the state of a UL subframe and if the SCell is in thestate of a DL subframe or special subframe at step 1011, the UE receivesthe PDSCH at the n^(th) subframe of the SCell at step 1015. This is thecase of m<n such that the PDSCH is received at a subframe located laterthan the subframe carrying the PDCCH. Afterward, the UE transmits theHARQ ACK/NACK corresponding to the PDSCH at the UL subframe of thePCell, according to the HARQ ACK/NACK transmission timing defined inrule 3 in a case of the first exemplary embodiment and the HARQ ACK/NACKtransmission timing defined in rules 3 and 4 in a case of the secondexemplary embodiment, at step 1017. Afterward, the procedure returns tostep 1001.

Although not depicted in the drawing, if it is determined that the PDCCHreceived is for scheduling the PDSCHs of both the PCell and SCell atstep 1003, the UE's PDSCH reception procedure in the PCell goes to step1005. Meanwhile, the UE's PDSCH reception procedure in the SCell goes tostep 1011.

The first to third exemplary embodiments are applied to the case wherethe number of UL subframes defined in the TDD uplink-downlinkconfiguration of the PCell is greater than the number of UL subframesdefined in the TDD uplink-downlink configuration of the SCell. If theSCell is in the state of a UL subframe at the same timing, the PCellshould be in the UL subframe. That is, the position of the UL subframeof the PCell is always of a superset as compared to the UL subframe ofthe SCell in view of the UL subframe. Accordingly, when the UE transmitsthe HARQ ACK/NACK corresponding to the PDSCH of the SCell at the ULsubframe of the PCell, it is possible to minimize delay. The combinationof the TDD uplink-downlink configurations available for the PCell andSCell from the reference point of the TDD uplink-downlink configurationsdefined for the current LTE/LTE-A system can be summarized as shown inTable 7.

TABLE 7 Case Pcell Scell 1 0 1, 2, 3, 4, 5, 6 2 1 2, 4, 5 3 2 5 4 3 4, 55 4 5 6 5 — 7 6 1, 2, 3, 4, 5

In Table 7, if the PCell is configured with the TDD uplink-downlinkconfiguration #6, the SCell can be configured with one of the TDDuplink-downlink configuration #1, TDD uplink-downlink configuration #2,TDD uplink-downlink configuration #3, TDD uplink-downlink configuration#4, and TDD uplink-downlink configuration #5. The first to thirdexemplary embodiments can be modified in various ways.

For example, the cross carrier scheduling can be allowed only when boththe PCell and SCell are in the state of a DL subframe or specialsubframe at the same timing. That is, if the PCell is in the state of aUL subframe and the SCell is in the state of a DL subframe at a certaintiming, the cross carrier scheduling is not permitted. Accordingly, theHARQ ACK/NACK transmission timing is determined according to rules 1 and2 only.

For a modified example, if there is a plurality of subframes satisfyingrule 3 in the first exemplary embodiment, the HARQ ACK/NACK transmissiontiming is determined as the subframe closest to the subframe carryingthe PDSCH in the SCell, in addition to rule 3.

For another modified example, it is possible to restrict thecombinations of the TDD uplink-downlink configurations that areavailable in the carrier aggregation mode according to the transmissionperiod of the special subframe, with another condition in addition tothe conditions of Table 7. That is, the TDD uplink-downlinkconfigurations #0, #6, #1, and #2 having the special subframetransmission period of 5 ms are categorized into group #1, and the TDDuplink-downlink configurations #3, #4, and #5 having the specialsubframe transmission period of 10 ms are categorized into group #2. Ineach group, the HARQ ACK/NACK transmission timing can be defined underthe conditions proposed in the description of Table 7 and rules definedin the first and second exemplary embodiments.

Fourth Exemplary Embodiment

Unlike the first to third exemplary embodiments, the fourth exemplaryembodiment is directed to the case where the TDD uplink-downlinkconfigurations of the PCell and SCell have no restriction.

A description is made of the operation according to the fourth exemplaryembodiment adopting rule 5 in addition to rules 1 and 2.

FIG. 11 is a diagram illustrating a timing relationship between a PDSCHand an uplink HARQ ACK/NACK according to a fourth exemplary embodimentof the present invention. FIG. 11 is directed to the TDD systemoperating with two aggregated component carriers in which the PCell isconfigured with the TDD uplink-downlink configuration #1 and the SCellis configured with the TDD uplink-downlink configuration #0. In FIG. 11,the timing relationship among PDCCH, PDSCH, and PUCCH in the PCell andthe timing relationship among PDCCH, PDSCH, and PUCCH in the SCell thatare defined for the legacy LTE system are expressed by solid linearrows. The start point of each solid line arrow denotes the DL subframecarrying PDCCH and PDSCH, and the end point of each solid line arrowdenotes the UL subframe carrying PUCCH.

Referring to FIG. 11, the transmission timing of HARQ ACK/NACKcorresponding to the PDSCH of the SCell according to the proposedinvention is expressed as dotted arrow. Although FIG. 11 is directed tothe case of adopting the cross carrier scheduling, this method can beapplied for determining the HARQ ACK/NACK transmission timing in thecase of adopting the self-scheduling too.

In the exemplary case of FIG. 11, the dotted link arrow starting at a Dor S subframe of the PCell and ending at a D or S subframe of the SCellexpress the cross carrier scheduling operation in which the PDCCHtransmitted at the D or S subframe of the PCell schedules the PDSCH tobe transmitted at the D or S subframe of the SCell. Also, the dottedline arrow starting at the D or S subframe of the SCell and ending at aU subframe of the PCell expresses an operation in which the HARQACK/NACK corresponding to the PDSCH transmitted at the D or S subframeof the SCell is transmitted at U subframe of the PCell.

In FIG. 11, the PCell follows the HARQ ACK/NACK transmission timingaccording to the TDD uplink-downlink configuration #1 defined in thelegacy LTE regardless of the use of carrier aggregation according torule 1. The SCell follows the HARQ ACK/NACK transmission timing of thePCell aggregated with the SCell regardless of the TDD uplink-downlinkconfiguration of the SCell according to rule 2.

In the exemplary case of FIG. 11, if the PDSCH is transmitted at thesubframe #1 1107 of i^(th) radio frame through the PCell tocross-carrier schedule the SCell, the PDSCH is transmitted at thesubframe #1 1122 of the i^(th) radio frame through the SCell. The HARQACK/NACK corresponding to the PDSCH of the SCell is transmitted at thesubframe #7 1113 of the i^(th) radio frame of the PCell according to thetransmission timing of the HARQ ACK/NACK corresponding to the subframe#1 1107 of the PCell according to rule 2.

If the PDCCH is transmitted at the subframe #5 of the i^(th) radio framethrough the PCell to cross carrier schedule the SCell, the PDSCH istransmitted at the subframe #5 1126 of the i^(th) radio frame of theSCell. The HARQ ACK/NACK corresponding to the PDSCH of the SCell istransmitted at the subframe #2 1118 of the (i+1)^(th) radio framethrough the PCell according to the transmission timing of the HARQACK/NACK corresponding to the subframe #5 1111 of the PCell according torule 2.

In the exemplary case of FIG. 11, however, the PCell is in the state ofa DL subframe and the SCell is in the state of a UL subframe at thesubframe #4 1110 and 1125 of the i^(th) radio frame at the same timing.Accordingly, the PDSCH as DL data of the SCell cannot be transmitted atthe subframe #4 1125 of the SCell. This means that the cross carrierscheduling cannot operate at the corresponding subframe.

-   -   Rule 5: if the SCell is in the state of a UL subframe and the        PCell is in the state of a DL subframe at the same timing, the        PDSCH of the SCell cannot be cross-carrier scheduled at the        corresponding subframe.

In this case, the PDCCH for scheduling PDSCH of the PCell and the PDSCHcan be transmitted at the corresponding subframe #4 of the PCell. TheHARQ ACK/NACK corresponding to the PDSCH of the PCell is transmitted atthe subframe #8 of the PCell according to the conventional timingrelationship of the HARQ of the PCell.

The HARQ ACK/NACK transmission timing according to the fourth exemplaryembodiment can be summarized as shown in Table 8. If the PDSCHtransmitted by the eNB at (n−j)^(th) subframe is received, the UEtransmits uplink HARQ ACK/NACK corresponding to the PDSCH at the n^(th)subframe. Here, j is an element of a set J which is defined as shown inTable 8. Table 8 is directed to the case where the PCell is configuredwith the TDD uplink-downlink configuration #1, the SCell is configuredwith the TDD uplink-downlink configuration #0, and the HARQ ACK/NACKscorresponding to the PDSCHs transmitted through the PCell and SCell aretransmitted through the PCell.

TABLE 8 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 1 — — 7, 6 4— — — 7, 6 4 — 0 — — 7, 6 — — — — 7, 6 — —

The eNB procedure according to the fourth exemplary embodiment isperformed as described with reference to FIG. 9 with the addition ofrule 5. The UE procedure according to the fourth exemplary embodiment isperformed as described with reference to FIG. 10 with the addition ofrule 5.

Although the first to fourth exemplary embodiments are directed to themethod for transmitting HARQ ACK/NACK in PUCCH, the present invention isnot limited thereto. Even when transmitting the HARQ ACK/NACK in thePUSCH, the HARQ ACK/NACK is transmitted according to the timingrelationship so as to maintain the consistency of HARQ ACK/NACKtransmission timing. For example, in the exemplary case of FIG. 6, theHARQ ACK/NACK corresponding to the PDSCH transmitted at the subframe #9630 of the i^(th) radio frame of the SCell is transmitted at thesubframe #3 of the (i+1)^(th) radio frame according to the SCell's owntiming relationship. In a case where the UE transmits PUSCH at thesubframe #3 634 of the (i+1)^(th) radio frame, however, the HARQACK/NACK can be transmitted in the PUSCH at the subframe #3 of theSCell. Even in this case, rule 2 is applied such that the PUCCH, or ifPUSCH has been scheduled, the HARQ ACK/NACK can be transmitted in thePUSCH.

Typically in the legacy LTE and LTE-A systems, the radio resource fortransmitting the HARQ ACK/NACK is calculated automatically from theControl Channel Element (CCE) of the PDCCH for scheduling the PDSCHcorresponding to the HARQ ACK/NACK. The CCE is a unit of the PDCCH. OneCCE is composed of total 36 Resource Elements (REs). The RE is a basicunit of radio resource of the LTE and LTE-A systems and is defined as acombination of a subcarrier in the frequency domain and an OFDM symbolin the time domain.

If one PDCCH is used for scheduling PDSCH to be transmitted at aplurality of subframes, it is possible to cross-carrier schedule thePDSCH to be transmitted at the subframe #1 622 of the SCell(hereinafter, referred to as PDSCH 1) and the PDSCH to be transmitted atthe subframe #4 625 of the SCell (hereinafter, referred to as PDSCH 2)with one PDCCH transmitted at the subframe #1 676 of the PCellsimultaneously. At this time, the transmission resource for the HARQACK/NACKs corresponding to the PDSCHs of the PCell and SCell should bedefined, respectively.

In case that the transmission timing of the PDSCH 1 is earlier than thatof the PDSCH 2, the transmission resource of the HARQ ACK/NACKcorresponding to the PDSCH 1 is calculated from the CCE having thelowest index (n_CCE). Meanwhile, the transmission resource of the HARQACK/NACK corresponding to the PDSCH 2 is calculated from the CCE havingthe index of n_CCE+1.

FIG. 12 is a block diagram illustrating a configuration of an eNBaccording to any of the first to fourth exemplary embodiments of thepresent invention.

Referring to FIG. 12, the eNB includes a transmission part (TX)comprising a Carrier aggregation/timing controller 1201, a scheduler1203, a PDCCH block 1205, a PDSCH block 1216, and a multiplexer 1215;and a reception part (RX) comprising a PUCCH block 1239 and ademultiplexer 1249. The PDCCH block 1205 of the transmission partincludes a DCI formatter 1207, a channel coder 1209, a rate matcher 1211and a modulator 1213; and the PDSCH block 1216 includes a data buffer1217, a channel coder 1219, a rate matcher 1221, and a modulator 1223.The PUCCH block of the reception part includes a demodulator 1247, achannel decoder 1243, and an HARQ ACK/NACK acquirer 1241.

The carrier aggregation/timing controller 1201 determines the carrieraggregation scheme and the timing relationship among the physicalchannels for the UE to be scheduled by referencing the data amount to betransmitted to the UE and the resource amount available in the systemand notifies the scheduler 1203 and the PUCCH block 1239 of thedetermination result. Here, the timing relationship is determinedaccording to the method according to one of the above-describedexemplary embodiments of the present invention.

The carrier aggregation/timing controller 1201 controls to transmit tothe UE the downlink physical channels for at least one of the first andsecond cells. The carrier aggregation/timing controller 1201 controls toreceive the uplink physical channel corresponding to the downlinkphysical channel at a predetermined timing through the first cell. Thecarrier aggregation/timing controller 1201 also control such that theuplink physical channel corresponding to the downlink physical channelof the second cell is received at the uplink physical channel receptiontiming of the first cell.

In this case, if the downlink physical channels about the first andsecond cells are transmitted to the UE at the same timing, the carrieraggregation/timing controller 1201 configures the uplink physicalchannel reception timing of the second cell to be identical with theuplink physical channel reception timing of the first cell. Meanwhile,if the downlink physical channels of the first and second cells are nottransmitted at the same timing, the carrier aggregation/timingcontroller 1201 configures such that the uplink physical channelreception timing of the second cell is identical with the uplinkphysical channel reception timing corresponding to the downlink subframeof the first cell which is closest to the downlink physical channelreception timing of the second cell. In this case, the uplink physicalchannels for the first and second cells can be received as distributedacross the uplink subframes as equally as possible.

In a case where the first cell is in the state of a DL subframe and thesecond cell is in the state of a UL subframe, the carrieraggregation/timing controller 1201 may not cross-carrier schedule thesecond cell at the corresponding timing.

The PDCCH block 1205 generates DCI by means of the DCI formatter 1207under the control of the scheduler 1203. The DCI is channel-coded withthe addition of error correction capability by means of the channelcoder 1209 and then rate-matched to the resource amount to be mappedthereto by means of the rate matcher 1211. The rate-matched DCI ismodulated by the modulator 1213 and multiplexed with other signals bythe multiplexer 1215. The multiplexed signals are converted into OFDMsignals so as to be transmitted to the UE.

The PDSCH block 1215 receives PDSCH data in the data buffer 1217 underthe control of the scheduler 1203. The PDSCH data is channel-coded bymeans of the channel coder 1219 and then rate-matched to the resourceamount to be mapped thereto by means of the rate matcher 1221. Therate-matched PDSCH data is modulated by the modulator 1223 andmultiplexed with other signals by the multiplexer 1215. The multiplexedsignals are converted into OFDM signals so as to be transmitted to theUE.

The PUCCH block 1239 of the receiver separates PUCCH signals from thereceived signal by means of the demultiplexer 1249 and the demodulator1247 performs demodulation on the PUSCH signal. The PUCCH block 1239decodes the demodulated PUCCH signal by means of the channel decoder1243 and acquires HARQ ACK/NACK by means of the HARQ ACK/NACK acquirer1241. The acquired HARQ ACK/NACK is provided to the scheduler so as tobe used for determining whether to retransmit the PDSCH. The acquiredHARQ ACK/NACK is also provided to the carrier aggregation/timingcontroller 1201 so as to be used for determining the PDSCH transmissiontiming.

FIG. 13 is a block diagram illustrating a configuration of a UEaccording to any of the first to fourth exemplary embodiments of thepresent invention.

Referring to FIG. 13, the UE includes a transmission part (TX)comprising a carrier aggregation/timing controller 1301, a PUCCH block1305, and a multiplexer 1315; and a reception part (RX) comprising aPDSCH block 1330, a PDCCH block 1339, a demultiplexer 1349. The PUCCHblock 1305 of the transmission part includes an HARQ ACK/NACK formatter1307, a channel coder 1309, and a modulator 1313. The PDSCH block 1330of the reception part includes a demodulator 1337, a de-rate matcher1335, a channel decoder 1333, and a data acquirer 1331. The PDCCH block1339 includes a demodulator 1347, a de-rate matcher 1345, a channeldecoder 1343, and a DCI acquirer 1341.

The carrier aggregation/timing controller 1301 adjusts the carrieraggregation state of the UE based on the DCI received from the eNB. Thecarrier aggregation and timing controller 1301 determines the carrierfor receiving PDSCH in cross-carrier scheduling mode and the timingrelationship among the physical channel and notifies the PUCCH block1305, PDSCH block 1330, and PDCCH block 1339 of the determinationresult. The timing relationship is determined according to one of theabove-described exemplary embodiments of the present invention.

In more detail, the carrier aggregation/timing controller 1301 controlsto receive the downlink physical channel transmitted by the eNB throughat least one of the first and second cells. The carrieraggregation/timing controller 1301 also controls such that the uplinkphysical channel is transmitted at a predetermined timing through thefirst cell. The carrier aggregation/timing controller 1301 also controlssuch that the uplink physical channel of the second cell is transmittedat the uplink physical channel transmission timing of the first cell.

In a case where the downlink physical channels of the first and secondcells are transmitted from the eNB at the same timing, the carrieraggregation/timing controller 1301 configures such that the uplinkphysical channel transmission timing of the second cell matches theuplink physical channel transmission timing of the first cell. Also,when the downlink physical channels of the first and second cells arereceived from the eNB at different timings, the carrieraggregation/timing controller 1301 configures the uplink physicaltransmission timing of the second cell to match the uplink physicalchannel transmission timing configured for the downlink subframe of thefirst cell which is closest to the downlink physical transmission timingof the second cell.

In this case, the carrier aggregation/timing controller 1301 can controlsuch that the uplink physical channels of the first and second cells aretransmitted to the eNB as distributed across the uplink subframes asequally as possible.

The PUCCH block 1305 of the transmitter configures the HARQ ACK/NACK bymeans of the HARQ ACK/NACK formatter 1307 under the timing control ofthe carrier aggregation/timing controller 1201. The HARQ ACK/NACK ischannel coded with the addition of error correction code capability bythe channel coder 1309, modulated by the modulator 1313, and multiplexedwith other signals by the multiplexer 1315.

The PDSCH block 1330 of the reception part separates the PDSCH signalfrom the received signal by means of the demultiplexer 1349. The PDSCHblock 1330 demodulates the PDSCH signal by means of the demodulator 1337and reconfigures the symbols before rate matching by means of thede-rate matcher 1335. The PDSCH block 1330 decodes the reconfiguredsymbols by means of the channel decoder 1333 and acquires PDSCH data bymeans of the data acquirer 1331. The data acquirer 1331 notifies thePUSCH block 1305 of the error occurrence in the decoding result tocontrol generation of the uplink HARQ ACK/NACK. The data acquirer 1331provides the carrier aggregation/timing controller 1301 with thedecoding result to adjust the HARQ ACK/NACK transmission timing.

The PDCCH block 1339 separates PDCCH signal from the received signal bymeans of the demultiplexer 1349. The PDCCH block 1339 demodulates theseparated PDCCH signal by means of the demodulator 1347 and decodes thedemodulated signal by means of the channel decoder 1343. The PDCCH block1339 acquires DCI from the decoded PDCCH signal by means of the DCIacquirer 1341. The acquired DCI is provided to the carrieraggregation/timing controller 1301 so as to be used for adjusting theHARQ ACK/NACK transmission timing.

As described above, the physical channel transmission/reception timingconfiguration method and apparatus of exemplary embodiments of thepresent invention is capable of minimizing data and/or control channeltransmission/reception error and transmission delay by defining thetransmission timing among the physical data and control channels in theTDD wireless communication system securing broadband resource throughcarrier aggregation.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for communication of a base station in acommunication system, the method comprising: transmitting, to aterminal, information for a first time division duplex (TDD)uplink/downlink (UL/DL) configuration for a primary cell; transmitting,to the terminal, information for a second TDD UL/DL configuration for asecondary cell; transmitting, to the terminal, first data on a firstsubframe of the secondary cell based on the second TDD UL/DLconfiguration to a terminal; and receiving, from the terminal, firstfeedback information corresponding to the first data on a secondsubframe of the primary cell based on the first TDD UL/DL configuration.2. The method of claim 1, further comprising: transmitting, to theterminal, second data on a third subframe of the primary cell based onthe first TDD UL/DL configuration, the third subframe corresponding tothe first subframe of the secondary cell; and receiving, from theterminal, second feedback information corresponding to the second dataon the second subframe of the primary cell.
 3. The method of claim 1,further comprising: transmitting, to the terminal, control informationfor scheduling the first data on the primary cell.
 4. The method ofclaim 1, wherein the receiving of the first feedback informationcorresponding to the first data comprises: receiving, from the terminal,the feedback information corresponding to the first data on the secondsubframe of the primary cell based on the first TDD UL/DL configuration,if any subframe of the second TDD UL/DL configuration corresponding toan uplink subframe of the first TDD UL/DL configuration is an uplinksubframe.
 5. The method of claim 1, wherein the first UL/DLconfiguration is TDD UL/DL configuration 3 and the second TDD UL/DLconfiguration is TDD UL/DL configuration 1, or wherein the first TDDUL/DL configuration is TDD UL/DL configuration 3 and the second TDDUL/DL configuration is TDD UL/DL configuration 4, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 6 and the second TDDUL/DL configuration is TDD UL/DL configuration 2, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 0 and the second TDDUL/DL configuration is TDD UL/DL configuration 2, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 1 and the second TDDUL/DL configuration is TDD UL/DL configuration
 0. 6. A method forcommunication of a terminal in a communication system, the methodcomprising: receiving, from a base station, information for a first timedivision duplex (TDD) uplink/downlink (UL/DL) configuration for aprimary cell; receiving, from the base station, information for a secondTDD UL/DL configuration for a secondary cell; receiving, from the basestation, first data on a first subframe of the secondary cell based onthe second TDD UL/DL configuration to a terminal; and transmitting, tothe base station, first feedback information corresponding to the firstdata on a second subframe of the primary cell based on the first UL/DLconfiguration.
 7. The method of claim 6, further comprising: receiving,from the base station, second data on a third subframe of the primarycell based on the first UL/DL configuration, the third subframecorresponding to the first subframe of the secondary cell; andtransmitting, to the base station, second feedback informationcorresponding to the second data on the second subframe of the primarycell.
 8. The method of claim 6, further comprising: receiving, from thebase station, control information for scheduling the first data on theprimary cell.
 9. The method of claim 6, wherein the transmitting of thefirst feedback information corresponding to the first data comprises:transmitting, to the base station, the first feedback informationcorresponding to the first data on the second subframe of the primarycell based on the first UL/DL configuration, if any subframe of thesecond TDD UL/DL configuration corresponding to an uplink subframe ofthe first TDD UL/DL configuration is an uplink subframe.
 10. The methodof claim 6, wherein the first TDD UL/DL configuration is TDD UL/DLconfiguration 3 and the second TDD UL/DL configuration is TDD UL/DLconfiguration 1, or wherein the first TDD UL/DL configuration is TDDUL/DL configuration 3 and the second TDD UL/DL configuration is TDDUL/DL configuration 4, or wherein the first TDD UL/DL configuration isTDD UL/DL configuration 6 and the second TDD UL/DL configuration is TDDUL/DL configuration 2, or wherein the first TDD UL/DL configuration isTDD UL/DL configuration 0 and the second TDD UL/DL configuration is TDDUL/DL configuration 2, or wherein the first TDD UL/DL configuration isTDD UL/DL configuration 1 and the second TDD UL/DL configuration is TDDUL/DL configuration
 0. 11. A base station in a communication system, thebase station comprising: a transceiver configured to transmit andreceive a signal; and a controller coupled to the transceiver andconfigured to: transmit, to a terminal, information for a first timedivision duplex (TDD) uplink/downlink (UL/DL) configuration for aprimary cell, transmit, to the terminal, information for a second TDDUL/DL configuration for a secondary cell, transmit, to the terminal,first data on a first subframe of the secondary cell based on the secondTDD UL/DL configuration to a terminal, and receive, from the terminal,first feedback information corresponding to the first data on a secondsubframe of the primary cell based on the first UL/DL configuration. 12.The base station of claim 11, wherein the controller is furtherconfigured to: transmit, to the terminal, second data on a thirdsubframe of the primary cell based on the first UL/DL configuration, thethird subframe corresponding to the first subframe of the secondarycell, and receive, from the terminal, second feedback informationcorresponding to the second data on the second subframe of the primarycell.
 13. The base station of claim 11, wherein the controller isfurther configured to transmit, to the terminal, control information forscheduling the first data on the primary cell.
 14. The base station ofclaim 11, wherein the controller is further configured to receive, fromthe terminal, the feedback information corresponding to the first dataon the second subframe of the primary cell based on the first UL/DLconfiguration, if any subframe of the second TDD UL/DL configurationcorresponding to an uplink subframe of the first TDD UL/DL configurationis an uplink subframe.
 15. The base station of claim 11, wherein thefirst TDD UL/DL configuration is TDD UL/DL configuration 3 and thesecond TDD UL/DL configuration is TDD UL/DL configuration 1, or whereinthe first TDD UL/DL configuration is TDD UL/DL configuration 3 and thesecond TDD UL/DL configuration is TDD UL/DL configuration 4, or whereinthe first TDD UL/DL configuration is TDD UL/DL configuration 6 and thesecond TDD UL/DL configuration is TDD UL/DL configuration 2, or whereinthe first TDD UL/DL configuration is TDD UL/DL configuration 0 and thesecond TDD UL/DL configuration is TDD UL/DL configuration 2, or whereinthe first TDD UL/DL configuration is TDD UL/DL configuration 1 and thesecond TDD UL/DL configuration is TDD UL/DL configuration
 0. 16. Aterminal in a communication system, the terminal comprising: atransceiver configured to transmit and receive a signal; and acontroller coupled to the transceiver and configured to: receive, from abase station, information for a first time division duplex (TDD)uplink/downlink (UL/DL) configuration for a primary cell, receive, fromthe base station, information for a second TDD UL/DL configuration for asecondary cell, receive, from the base station, first data on a firstsubframe of the secondary cell based on the second TDD UL/DLconfiguration to a terminal, and transmit, to the base station, firstfeedback information corresponding to the first data on a secondsubframe of the primary cell based on the first UL/DL configuration. 17.The terminal of claim 16, wherein the controller is further configuredto: receive, from the base station, second data on a third subframe ofthe primary cell based on the first UL/DL configuration, the thirdsubframe corresponding to the first subframe of the secondary cell, andtransmit, to the base station, second feedback information correspondingto the second data on the second subframe of the primary cell.
 18. Theterminal of claim 16, wherein the controller is further configured to:receive, from the base station, control information for scheduling thefirst data on the primary cell.
 19. The terminal of claim 16, whereinthe controller is further configured to: transmit, to the base station,the first feedback information corresponding to the first data on thesecond subframe of the primary cell based on the first UL/DLconfiguration, if any subframe of the second TDD UL/DL configurationcorresponding to an uplink subframe of the first TDD UL/DL configurationis an uplink subframe.
 20. The terminal of claim 16, wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 3 and the second TDDUL/DL configuration is TDD UL/DL configuration 1, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 3 and the second TDDUL/DL configuration is TDD UL/DL configuration 4, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 6 and the second TDDUL/DL configuration is TDD UL/DL configuration 2, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 0 and the second TDDUL/DL configuration is TDD UL/DL configuration 2, or wherein the firstTDD UL/DL configuration is TDD UL/DL configuration 1 and the second TDDUL/DL configuration is TDD UL/DL configuration 0.